Intraluminal stent

ABSTRACT

An intraluminal stent made of a zig-zag or sinusoidal member defining a successive series of struts connected by apex sections and formed into a series of axially displaced hoop members wherein at least one of the hoop members has at least one strut connected to a strut of an adjacent hoop. The connected struts may be connected by spot welding, continuous welding, or suturing, for example, or by a bridging member connected to each strut, and may be spaced along the length of the stent in a pattern to form a connective spine. The number of zigs of the zig-zag member in each hoop member may be varied, as can the zig length. A plurality of connective spines may also be included.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/623,347, filed Nov. 15, 2000, now U.S. Pat. No. 6,730,117 which is aU.S. national phase application from International Patent ApplicationPCT/US99/04694, international filing date Mar. 4, 1999, which claimspriority based on U.S. Provisional Application Ser. No. 60/076,946,filed Mar. 5, 1998, which is hereby incorporated by reference.

FIELD OF INVENTION

This invention relates generally to intraluminal prostheses, and moreparticularly to intraluminal stents comprised of zig-zag or sinusoidalwire hoops.

BACKGROUND OF THE INVENTION

A common method of treating vessel diseases such as stenoses,strictures, thrombosis, or aneurysms involves placing a stent into theaffected vessel. Among other advantages, stents prevent vessels fromcollapsing, reinforce vessel walls, increase cross sectional area (andthereby volumetric flow), and restore or maintain healthy blood flow.Many stents have been developed, and the prior art includes a widevariety of types and methods for their manufacture.

SUMMARY OF THE INVENTION

The present invention is a generally cylindrical intraluminal stentincluding a plurality of circumferential wire hoops disposed insuccession along the axis of the stent. Each of the hoops has zig-zag orsinusoidal members defined by a successive series of struts connected byapex sections alternately pointing in opposite axial directions. Thestruts may be substantially straight sections connected to essentiallysharp apex sections in a jagged zig-zag configuration, or the apexsections may be more rounded so that together with the struts there isformed a sinusoidal configuration. The lengths of these struts may beuniform throughout the stent or may vary alternately or continuously.Likewise, the angles or radii of curvature and configurations of theapices may be uniform or may vary. To provide mechanical integrity,selected portions of the hoops may be secured against relative axialmovement, such as by spot welding overlying straight sections either inan individual hoop or in adjacent hoops. Such connections may also bemade with bridging members aligned with straight sections in adjacenthoops.

These connections (with or without intervening bridging members) may bedisposed in one or more linear or helical paths along the length of thestent, thus acting as stabilizing spines. Alternatively, theseconnections may be disposed in other preselected patterns, such asalternating around the circumference of the stent, to impart stabilityat these preselected locations.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures provided are for illustrative purposes, and are not drawn toscale. The expanded relative dimensions allow a better understanding ofthe present invention. One skilled in the art will readily determineactual dimensions based on information supplied in this specification.

FIG. 1 is a diagrammatic view of an exemplary embodiment of a stentaccording to this invention, where the tubular stent is shown openedalong a line parallel to the stent axis, and flattened; also shown aremandrel pins used in forming the stent.

FIG. 2 is a diagrammatic view of another exemplary embodiment of a stentaccording to this invention having multiple spines and axial andcircumferential offsets between facing apex sections, where the tubularstent is shown opened along a line parallel to the stent axis, andflattened; also shown are mandrel pins used in forming the stent.

FIG. 3 is a partial diagrammatic view of another exemplary embodiment ofa stent according to this invention having a plurality of longitudinalsections, the middle section having a different number of spines, adifferent number of zigs, and a different zig length than the endsections, where the tubular stent is shown opened along a line parallelto the stent axis, and flattened.

FIG. 4 is a diagrammatic view of another exemplary embodiment of a stentaccording to this invention having end portions with different zigcharacteristics relative to a center portion, where the tubular stent isshown opened along a line parallel to the stent axis, and flattened;also shown are mandrel pins used in forming the stent.

FIG. 5 is a diagrammatic view of another exemplary embodiment of a stentaccording to this invention having connecting members that includeseparate bridging members, where the tubular stent is shown opened alonga line parallel to the stent axis, and flattened; also shown are mandrelpins and weld holes used in forming the stent.

FIG. 6A is a diagrammatic view of an exemplary embodiment of a stentaccording to this invention having interdigitated zigs, where thetubular stent is shown opened along a line parallel to the stent axis,and flattened.

FIGS. 6B-6D are diagrammatic views of enlarged portions of the stent ofFIG. 6A, showing an exemplary end weld, and exemplary middle weld, andan exemplary radiopaque marker, respectively.

FIG. 6E is a diagrammatic view of an exemplary embodiment of stent 6A,where the stent is shown in its normal tubular configuration.

FIG. 6F is a diagrammatic view of an exemplary embodiment of a stentaccording to this invention having interdigitated zigs and a pluralityof longitudinal sections of different zig configurations, where thetubular stent is shown opened along a line parallel to the stent axis,and flattened

FIG. 7 is a partial side view of an exemplary embodiment of a stentaccording to this invention having alternating zig lengths, where thetubular stent is shown opened along a line parallel to the stent axis,and flattened.

FIG. 8 is a partial diagrammatic view of another exemplary embodiment ofa stent according to this invention having straight-edged apex sections,where the tubular stent is shown opened along a line parallel to thestent axis, and flattened.

FIG. 9 is a partial diagrammatic view of another exemplary embodiment ofa stent according to this invention having connecting members formed byelongated struts, where the tubular stent is shown opened along a lineparallel to the stent axis, and flattened; also shown are mandrel pinsused in forming the stent.

FIG. 10 is a partial diagrammatic view of the stent shown in FIG. 6Amounted on a mandrel during fabrication of the stent.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an exemplary stent 10 according to the presentinvention. Stent 10 is generally cylindrical and adapted to be insertedinto a lumen. Stent 10 has been cut longitudinally and laid flat forpurposes of illustration. Stent 10 is formed by winding a continuousfilament such as a wire 11 into a zig-zag or sinusoidal configurationand into a plurality of circumferential hoop members 12 a, 12 b, 12 cdisposed in succession along the axis of stent 10. Wire 11 is preferablynitinol wire, which provides a stent that auto-expands by shape memory,but it may be made of any suitable material, including stainless steeland thermoplastic polymers. Thus, the stent may be capable of deploymentby shape memory auto-expansion, thermal auto-expansion or balloonexpansion, as are well-known in the art. The width of the wire affectsthe radial force exerted by stent 10. Increasing the diameter of wire 11increases the radial force.

For convenience, the configuration of the wire is referred to throughouthaving a “zig-zag” shape with zigs or zig lengths. As so used herein,however, the term “zig-zag” encompasses not only a jagged zig-zag shapewhere the apex sections are relatively sharp and the struts aresubstantially straight, but also a sinusoidal shape where the apexsections are rounded and, together with the struts, form a shaperesembling a sine wave having an amplitude (zig length) and a period orwavelength (zig width). Similarly, although the apex sections may bereferred to as defining a zig angle, the angle may be more rounded suchthat lesser and greater angles may be more envisioned as smaller andlarger radii of curvature, respectively. Of course, the actual wireconfiguration may have a shape intermediate the jagged zig-zag androunded sine wave shapes, or may be even more rounded than a sine wave,and the apex sections may in fact have a truncated, straight edge ratherthan a rounded shape or sharp angle, as described herein later.

To form stent 10, wire 11 is wound around pins 13 on a mandrel (notshown). The mandrel is typically cylindrical (although other shapes maybe used as necessary to form stents of varying shapes) and of a diameterdetermined by the diameter of the vessel into which stent 10 is to beinserted. Typically, the mandrel diameter, and hence the intendeddiameter of stent 10, is slightly larger (for example, by onemillimeter) than the diameter of the vessel. The length of stent 10 isalso determined by the particular application.

Stent 10 is formed by winding wire 11 around pins 13 beginning at pointA in FIG. 1. Wire 11 is extended to and around pins 13 a, 13 b, 13 c andso forth. In this manner, zig-zag members are formed and defined by asuccessive series of substantially straight sections (struts) 14connected by apex sections 15 alternately pointing in opposite axialdirections. The winding continues in this manner around the mandreluntil a first hoop member 12 a is completed by winding wire 11 oncearound the circumference of the mandrel. Hoop member 12 a as shown inFIG. 1 has a circumference lying in a plane substantially perpendicularto the axis of the mandrel (and hence of stent 10). Once a first hoopmember 12 a is formed, wire 11 is extended from pin 13 d to and aroundpin 13 e. Winding then continues as before to form a second hoop member12 b adjacent to first hoop member 12 a. By forming hoop members in thismanner, adjacent hoops 12 a and 12 b are connected by the portion ofwire 11 extending between first hoop member 12 a and second hoop member12 b. At the completion of the second hoop member 12 b, wire 11 is againextended to the third hoop member 12 c, which is wound as before, and soforth until the desired number N of hoop members 12 are formed along thelength of stent 10. Thus, as shown in FIG. 1, the winding extends in aseries of hoops between hoops 12 a and hoop 12N, with the wire beginningat point A and ending at point B. After completion of winding, wire 11is typically cut so that the wire terminates short of points A and B,generally terminating within the first hoop 12 a and last hoop 12N,respectively, as described with reference to FIG. 6C herein later.

Stent 10 is removed from the mandrel and pins 13 a, 13 b, 13 c, etc.,prior to use. In the illustrated embodiment, each hoop member 12 has onepair of aligned, adjacent struts 14 a and 14 b. According to oneembodiment of the present invention, aligned, adjacent struts 14 a and14 b of the same hoop are welded together. Such welding may be spotwelding along the length of aligned, adjacent struts 14 a and 14 b, orit may be a continuous weld. In either case, a welded, connective spine16 is formed along the perimeter of stent 10. Connective spine 16typically winds around the circumference of stent 10 in an offsethelical fashion (the embodiment shown flat in FIG. 1 being cylindricalor tubular in actual use). Connective spine 16 provides strength andstability to stent 10 while preserving the flexibility of stent 10.During insertion of stent 10 into a vessel (described below), connectivespine 16 renders stent 10 easier to push through a catheter. As analternative to welding, connective spine 16 may be formed by connectingaligned, adjacent struts 14 a and 14 b according to any other suitableattachment means, including without limitation, tying, suturing, gluing,and stapling, with the glue or sutures being absorbable ornon-absorbable, and including the use of polymer-containing connections.

When stent 10 comprises thermally expandable nitinol, stent 10 isannealed before removal from the mandrel and pins 13 a, 13 b, 13 c,etc., at an annealing temperature for about one hour and then allowed tocool. This annealing temperature is desirably on the order of about 500°C., although any temperature sufficient to effect annealment of stent 10will suffice. During annealing, it may be necessary to secure thenitinol wire to the mandrel by wrapping bailing wire, a thicker gaugeand different material than the nitinol, around the stent on themandrel. Such annealing of nitinol wire imparts a memory to the nitinol,such that stent 10 will “remember” its annealed shape and return to itafter subsequent reconfiguration. This is a known property of nitinol,which has two distinct temperature-dependent phases, martensite andaustenite. Below a certain temperature (the martensite transitiontemperature), nitinol is martensitic; above a certain temperature (theaustenite transition temperature), it is austenitic. It is in theaustenitic phase that nitinol remembers its annealed configuration.

After annealing, stent 10 is removed from the mandrel on which it iswound to compress stent 10 into a configuration for introduction to abody passageway. Then, it is cooled to below its martensitic transitiontemperature. In this phase, nitinol is malleable and has virtually noresiliency. Thus, it can be easily compressed. Stent 10 can be easilyreturned to its annealed shape by heating it to a temperature above itsaustenite transition temperature. Above this temperature, the stentresumes its annealed configuration.

In its annealed configuration, stent 10 has a first diameter. This is arelatively large diameter that is the intended final diameter of stent10. In order to be inserted into a body vessel, stent 10 must becompressed such that it may be inserted into a catheter. As indicatedabove, with a nitinol stent, this is accomplished by cooling stent 10 tobelow its martensite transition temperature at which temperature stent10 is malleable and less resilient. Stent 10 can then be easilycompressed into a second, relatively small diameter for insertion intothe catheter. Once inside the catheter, stent 10 may be advanced to thedesired location within a body vessel according to methods known in theart and discharged from the catheter at that location. U.S. Pat. Nos.5,405,377 and 5,609,627, the disclosures of which are incorporatedherein by reference, contain additional details regarding the formation,use, and insertion of nitinol stents. Those patents are incorporatedherein by reference for their teaching on those subjects. When stainlesssteel, thermoplastic polymers, or other materials are used for wire 11,formation, use and insertion of stent 10 may be accomplished accordingto methods known to those skilled in the art.

Connective spine 16 lends strength, including hoop strength, to stent 10during and after implantation to better resist compressive forces withinthe vessel in which stent 10 is implanted. Connective spine 16 alsoallows flexibility, however, such that stent 10 may be easily compressedand expanded during the insertion process.

Particular features of the stent according to this embodiment of theinvention are illustrated in FIG. 2. As shown in FIG. 2, facing apexsections 15 of respective adjacent hoops of stent 10A are offsetcircumferentially from one another by a distance D1, as opposed toabutting one another. The offset allows stent 10A to be compressed to asmaller diameter (profile) for insertion into the catheter because theapex sections do not contact one another and hinder such compression.Increasing the axial distance D2 between apex sections 15 (the “ziggap”) also prevents interference between these sections duringcompression. The particular amount of offset and zig gap can beoptimized according to particular stent sizes and the desiredflexibility and compressed diameter as will be understood by thoseskilled in the art.

FIG. 2 also illustrates an embodiment of this invention having multiple,in this case two, connective spines 16. To form two connective spines16, two separate wires 11 and 11A are used to form stent 10A. As shownin FIG. 3, first wire 11 is formed in a zig-zag shape extending frompoint A to points B, C, D, E, F, G, H, I, J, K, L, M, N, O, P (etc.)sequentially. A second wire 11A is used to form the remainder of thestent by extending, in sequence from point E to points Q, R, S, A, T, U,V, W, X, Y, Z (etc.). In this manner, each hoop contains two pairs ofaligned, adjacent struts 14 a and 14 b. Aligned, adjacent struts 14 aand 14 b are then welded (or otherwise connected) to form connectivespines 16. In general, the number of wires 11, 11A, etc. used to formstent 10A directly corresponds to the number of connective spines 16that are desired. The strength and rigidity of stent 10A increase withthe addition of connective spines 16.

In the above configuration, the mandrel peg at each lettered point maybe considered to be one of a set of pegs corresponding to the wire towound about the set. Thus, pegs at points A, B, C, etc. above are a partof one set, and pegs E, Q, R, etc. above are part of a second set. Eachset, however, contains at least one common peg (for example, F in thefirst set and W in the second set) where both wires follow a common pathbetween the common pegs of the circumferentially adjoining sets. Thewires that form the common path (adjacent struts 14 a and 14 b) areconnected as described above.

FIG. 3 illustrates another alternative embodiment of this inventionwherein the zig length L₁ is varied within stent 10B. Zig length L₁ isthe distance between apex sections 15′ and 15″ measured in a directionparallel to the stent axis (vertical, in FIG. 3). As previouslyindicated, the zig length may similarly be described as the amplitude ofa sinusoidally shaped zig-zag. In this embodiment, the zig length at endsections 22 of stent 10B may be relatively short (relatively smallamplitude), while the zigs in middle section 20 of stent 10B arerelatively long (having greater amplitude). This may provide greaterradial force at the ends of stent 10B to assist in anchoring the stentin place in the vessel into which it is inserted by asserting a greaterforce against the walls of the vessel. This may also prevent blood fromleaking between stent 10B (when the stent is used in combination with agraft, as will be understood by those skilled in the art) and the vesselwall.

As illustrated in FIG. 3, there may also be a transition section 21 inwhich there is a transition zig length, between the short zig length atthe stent ends 22 and the long zig length in the stent middle 20, toprovide a gradual transition from the short to the long zigs. Typicalshort zig lengths are between two and three millimeters. Typical longzig lengths are between three-and-a-half and five millimeters. Theactual zig lengths may be optimized for particular applications as willbe understood to those skilled in the art based on the disclosureherein.

Another aspect of this invention involves the variation of the number ofzigs in each hoop member. Referring back to FIG. 1, a “zig” isconsidered to be the part of wire 11 extending from, for example, pointX to point Y to point Z. X-Y-Z in FIG. 1 is considered to represent onezig. Thus, each similarly-oriented apex section (i.e. each apex sectionpointing in the same direction) defines a zig. As previously indicated,the number of zigs in a hoop may be similarly described as the number ofperiods of a sinusoidally shaped zig-zag. In FIG. 1, each hoop memberhas five zigs. Using fewer zigs allows stent 10 to be compressed to asmaller insertion diameter (that is, fewer zigs decreases the profile ofstent 10). Increasing the number of zigs provides more support for anygraft covering used in conjunction with the stent, however, preventingthe possibility of in-folding of such graft layer.

FIG. 4 illustrates an alternative embodiment, not drawn to scale,wherein the center portion 20 of stent 10 has four zigs per hoop member12, a first zig length, and one connective spine 16; and the endportions 22 have six zigs per hoop member 12, a second zig length, andtwo connective spines 16. The second spines on both ends overlap twohoop members 12 of the center portion as a transition. The number ofconnective spines 16 can thus be varied within a stent to provide a morerigid portion at the ends and a more flexible portion in the middle. Thestent illustrated in FIG. 8 may have, for example, a wire diameter of0.007 inches, a 6.4 mm OD, a 6 mm ID, and a length of 100 mm. Other wirediameters slightly larger than 0.007 inches such as 0.008 or 0.009inches, for example, will suffice.

As shown in FIG. 9, another method of making connecting members maycomprise axially opposed apex sections 15 of adjacent hoops 12 beingaxially spaced from one another with one or both of the first and secondstruts 14′ of the connecting member elongated relative to the remainderof the struts 14 in the adjacent hoops. Such elongated struts 14′ maythus lie adjacent one another for at least some axial distance to permitconnection therebetween.

FIG. 5 illustrates a stent constructed according to another exemplaryembodiment of the present invention. Stent 30 is generally cylindricaland adapted to be inserted into a lumen. Stent 30 has been cutlongitudinally and laid flat for purposes of illustration. Stent 30 isformed by winding a continuous filament such as a wire 24 into a zig-zagconfiguration and into a plurality of circumferential hoop members 33,25 a . . . 25N, and 37 disposed in succession along the axis of stent30. Wire 24 is extended to and around pins 23 a, 23 b, 23 c and soforth. In this manner, zig-zag members are formed and defined by asuccessive series of substantially straight sections 34 connected byapex sections 35 alternately pointing in opposite axial directions. Thewinding continues in this manner around the mandrel until a first hoopmember 33 is completed by winding wire 24 once around the circumferenceof the mandrel. Winding then continues as before to form a second hoopmember 25 a adjacent to first hoop member 33 and a third hoop member 25b adjacent to second hoop member 25 a. Unlike hoop members 12 of stent10 as shown in FIG. 1, hoops 25 a . . . 25N are disposed at an angle toa plane perpendicular to the stent longitudinal axis; wire 24 thengradually spirals about the axis of stent 30 to form a coil. End hoops33 and 37, however, are disposed perpendicular to the stent axis. Thehelical configuration may be effected by each apex section in the helixhaving one connected strut longer than the other.

As further illustrated in FIG. 5, adjacent hoops are connected by aseparate bridging member 26 adjacent portions of respective straightsections 34 and 34A of axially opposed apex sections of adjacent hoops.As illustrated in FIG. 5, bridging member 26 is preferably linear andaligned with aligned struts 34 and 34A of proximate sections of adjacenthoops 25 _(i) and 25 _(i+1), although non-linear and non-alignedbridging members are also contemplated in accordance with the presentinvention, as may be appreciated by those skilled in the art. Separatebridging member 26 may be the same material as or a different materialthan wire 24 used to form hoops 33, 25 a-N, and 37 of stent 30,depending on the desired flexibility and compressed stent diameter. Inone embodiment, separate bridging member 26 and wire 24 are made of thesame material, for example, nitinol. Separate bridging member 26 andwire 24 may have approximately the same or different cross sectionaldimensions (i.e. the same or a different wire gauge), depending on thedesired implementation.

An exemplary separate bridging member 26 is preferably formed byextending a wire segment between a pair of pins 28 extending from themandrel proximate straight sections 34 and 34A of adjacent hoops 25 _(i)and 25 _(i+1). These pins 28 and 29 are in addition to pins 23 a, 23 b,etc. used to form zig-zag members of the respective hoops of stent 30.Wire-segment bridging member 26 is extended between pins 28 and bothends are at least partially wrapped around the pins, preferably withenough tension to remove unwanted slack from the wire, although variousamounts of slack may be maintained, depending on the desired rigidity,flexibility, and compressed diameter of stent 30.

To effect welds during manufacture of a stent of the present invention,and as shown in FIG. 5, ball weld cutting holes 29 may be formed in themandrel providing access to the mandrel interior, the holes desirablypositioned such that sections to be welded, such as aligned, adjacentstruts 34 and 34A, lie approximately above the ball weld cutting holes.In this way, a laser may be focused into ball weld cutting holes 29 to:(i) remove excess wire extending past ball weld cutting holes 29 andaround the pins, and (ii) weld the remaining wire segment between thealigned, adjacent struts of adjacent hoops as, for example, bridgingmember 26 between struts 34 and 34A. The connection between bridgingmember 26 and struts 34 and 34A may, instead of a weld, may beaccomplished according to any other suitable attachment means, includingwithout limitation, tying, suturing, gluing, and stapling, with the glueor sutures being absorbable or non-absorbable, and including the use ofpolymer-containing connections.

As further illustrated in FIG. 5, a stent 30 constructed in accordancewith the present invention may further include the plurality of separatebridging members 26 a-26N disposed in succession along the length of thestent. Each successive separate bridging member 26 _(i) connects asuccessive pair of adjacent hoops along the axis of stent 30 to form aspine along the length of stent 30. The spine may be a continuous spineof helically-aligned bridging members, similar to the spine illustratedin FIG. 1, or may be constructed of a single bridging member connectinga plurality of hoops along the length of the stent. Alternatively, asshown in FIG. 5, each successive connecting member 26 _(i) may becircumferentially offset from a preceding connecting member with respectto the axis of stent 30 to define a helical spine of disjointedconnecting members, or a “floating” spine. Hoop members 33, 37 disposedat each end of stent 30 may have the apex sections that point outwardlyfrom the stent disposed in common planes perpendicular to the axis ofstent 30, such as apex sections 35′ of hoop 34 along plane I, as shownin FIG. 5.

To make this transition from hoops other than perpendicular end hoops 33and 37 to the end hoops, the successive lengths of struts in the endhoops may be reduced along the circumference of the hoops. Additionally,or in the alternative, the successive amount of interdigitation(overlap) between apex sections of adjacent hoops may increase along thecircumference of end hoops 33 and 37 approaching the end of wire 24.

FIGS. 6A-6E illustrate stent 40, another exemplary embodiment of thepresent invention. In stent 40, adjacent hoops 42 a . . . 42N areinterdigitated with respect to one another. That is, oppositely directedapex sections 44A and 44B in respective adjacent hoops 42 b and 42 c,for example, overlap one another axially, or expressed another way, theyintersect a common plane angularly disposed with respect to the axis ofstent 40. Hoop members 42 a . . . 42N also preferably have zigssubstantially in phase circumferentially about stent 40. Stent 40comprises a continuous series of similarly-oriented apex sections 44Aarranged in a helix in which each hoop 42 i comprises one 360-degreewrap of the helix. Each apex section in the helix comprises two strutsattached thereto, in this embodiment with one strut being longer thanthe other to effect the helical progression. Such a hoop configurationis also seen in U.S. Pat. No. 5,575,816 to Rudnick et al., which isincorporated herein by reference and which illustrates a variety ofother interdigitated stent configurations.

In a pair of adjacent hoops, such as hoops 42 b and 42 c, one strut 45of hoop member 42 b is aligned with and overlaps strut 45 of hoop member42 c, and is connected to form a connecting member 48 a-N, preferably byspot welding, although other connection mechanisms are contemplated aswill be understood by those skilled in the art. Interdigitated stent 40in its normal tubular form is illustrated in FIG. 6E.

Referring now to FIG. 10, there is shown a helical stent 110,corresponding to the layout shown in FIG. 6A, on a tubular mandrel 114.Helical stent 110 or a helical segment thereof, as shown in FIG. 10, maybe constructed by winding N filaments 111, where N is a whole number ofat least 1, around N respective sets of pegs 112 a-N on a tubularmandrel 114. As shown in FIG. 11, N=1. Each of the N sets includes atleast three axially offset pegs, such as pegs 112 a, 112 b, and 112 c,defining a zig-zag configuration at a preselected axial location onmandrel 114, with circumferentially successive pairs of pegs (pegs 112 cand 112 d, for example) being axially offset in a preselected directionfrom the pair which precedes it (pegs 112 a and 112 b) so as to form ahelical zig-zag pattern repeatedly traversing the mandrel along thelength of stent 110. Each traversal of a preselected angular portion ofmandrel 114 by pegs 112 a-N includes at least one common peg (112 r, forexample) approximately 360° helically offset from an adjacent peg (112k). The peg adjacent the common peg may be part of the same set of pegs(for instance, where N is equal to 1) or a part of a circumferentiallyadjoining set of pegs (where N is greater than 1). Common peg 112 rprovides at least one circumferential location in each traversal of apreselected angular portion, where a portion of the filament in eachtraversal of a preselected angular portion contacts a portion of afilament in an adjacent traversal. This contact may be with the samefilament (for instance, where N is equal to 1 as shown in FIG. 11) orwith an different filament (where N is greater than 1). A connection 48is formed along the contacting adjacent filaments or portions thereof,forming a circumferential stent or segment thereof comprised of ahelical succession of zig-zags. Thus, the wire configuration may form ahelix as shown in FIGS. 6A, 6E, and 11, or a double- or othermultiple-helix (not shown). As shown in FIG. 6A, a single filament (N=1)repeatedly traverses the mandrel (not shown) along a single set of pegs,wherein in each angular traversal of 450° there is a common peg 13′approximately (in this case slightly greater than) 360° offset from anadjacent peg 13′ (the pegs immediately adjacent each connecting member48 a-N).

Stent 40 as shown in FIG. 6A comprises a plurality of connecting members48 a-N disposed in succession along the stent axis between pairs ofadjacent hoops. Each set of connecting members 48 a-N connects asuccessive pair of adjacent hoops along the axis of stent 40 to form aspine along the length of the stent. As with the successive connectingmembers 26 of FIG. 5, each pair of successive connecting members 48 _(i)is circumferentially offset from a preceding connecting member 48 _(i−1)with respect to the axis of stent 40.

As shown in FIG. 6A, each apex section 44B includes an apex angle α anda zig width W measured between adjacent, apex sections 44A opposite apexsection 44B. As shown in FIG. 6A, the included angle (zig angle) and zigwidth of apex sections 44B are essentially uniform throughout stent 40,except for the apex sections 44B′ and 44B″ that include the struts 45that form connecting members 48 a-N. Apex sections 44B′ and 44B″ have anon-uniform zig angle and resulting zig width as compared to apexsections 44B. As shown in FIG. 6A, the zig including apex section 44B′has a greater included angle and has a greater zig width than theuniform angle and width included by apex sections 44B; apex section 44B″has a lesser included angle and smaller zig width than the uniform angleand width. As shown in FIG. 6A, stent 40 comprises a helicalconfiguration having 4 zigs per 360-degree wrap, each such wrapcomprising a hoop. Apex section 44B′ is spaced 5 zigs from eachpreceding 44B′; apex section 44B″ is similarly spaced 5 zigs from eachpreceding 44B″. Thus, for a stent with N zigs, the non-uniform zigs arespaced every N+1 zigs to achieve the helical pattern of connections 48a-N as shown in FIG. 6A. In other words, for the 4-zig stent of 6A,connecting members 48 a-N are uniformly distributed in a helical spacingapproximately every 450° along the length of the stent to form a helicalspine. Other helical or non-helical spine configurations may be achievedby spacing the non-uniform zigs differently.

FIGS. 6B and 6C illustrate exemplary spot weld configurations withinstent 40. For adjacent, aligned struts 48 b-48 _(N−1), the portion ofeach strut adjacent one another may be of a first length having a weld54 of length L₁, as shown in FIG. 6B. For adjacent, aligned struts 48 aand 48N on the end hoops, however, the portions of each strut adjacentone another may be longer, and thus may include a weld 56 of length L₂,as shown in FIG. 6B. To avoid sharp edges protruding from the stent, endstrut 58 may be cut, as shown in FIG. 6C, so that it terminates adistance D from weld 56 in a position that lies short of plane II onwhich apex section 46 lies. For instance, the end of end strut 58 may becut so that it terminates a distance above plane II equivalent to theradius R of apex section 46. As shown in FIG. 6A, end strut 58 has notyet been cut, but may be cut using ball weld cutting hole 29, similar tothose described with reference to FIG. 5.

FIG. 6D illustrates an exemplary radiopaque marker 59 that may be usedwith the present invention. Marker 59 may comprise a radiopaquesubstance, such as a platinum wire, wrapped about a strut on an endhoops. This substance thus defines a surface having a differentradiopacity than the area surrounding it. This same effect may beachieved by marking a particular location of the stent with an area oflower radiopacity. One or more markers 59 may be disposed on one or bothof the end hoops. Marker 59 generally may be tightly wound with nounderlying strut visible to the unaided eye, and may extend 1-2 wrapspast the start of the radius where the strut bends to form the apexsection. Marker 59 is typically configured without sharp edges at theends.

FIG. 6F is a diagrammatic view of an exemplary embodiment of stent 60,opened along a line parallel to the stent axis and flattened, havinginterdigitated zigs, similar to stent 40 of FIGS. 6A-E, but additionallyhaving a plurality of longitudinal sections, similar to stent 10C asshown in FIG. 4. Middle section 62 has a longer zig length than endsections 64, and transition sections 63 intermediate the middle sectionand each end section have a zig length that is between the length of themiddle and the end section zigs.

FIG. 7 illustrates still another stent 70 constructed in accordance withthe present invention. Stent 70 has been cut longitudinally and laidflat for purposes of illustration. Stent 70 is formed by winding a wirearound pins extending from a mandrel somewhat similar to the mannerdescribed with reference to FIG. 1, although the pins are configuredsuch that zig-zag sections of respective hoops 76 a, 76 b, 76 c, 76 dare of varying height and varying width. In the embodiment illustratedin FIG. 7, the width of the zig length alternates between distance XXand WW along each hoop circumferentially about stent 70. The zig lengthsimilarly alternates between length YY and ZZ moving along each hoopcircumferentially about stent 70. Length ZZ is approximately half oflength YY in FIG. 7, although other length variations are contemplated.Adjacent hoops, such as hoops 76 a and 76 b, are phase-shifted byapproximately and 180 degrees and inverted with respect to one another.Accordingly, apex sections 65 and 66 of hoop member 76 a pass through aplane perpendicular to the axis of stent 60 determined by the positionsof oppositely directed alternate apex sections 67 and 68 in adjacenthoop 76 b. The configuration of FIG. 7 may be incorporated intotransition segments of other stents constructed according to the presentinvention.

A series of separate bridging members 72 a, 72 b, and 72 c connectsadjacent hoops 76 a and 76 b, as shown in FIG. 7. Another series ofseparate connecting members 74 a and 74 b connects adjacent hoops 62 band 62 c. Bridging members 72 a, 72 b, and 72 c are angled relative tothe tubular axis of stent 70 in opposite orientations than bridgingmembers 74 a and 74 b, to counter rotating effects in stents in whichbridging members between successive pairs of adjacent hoops are orientedin the same direction. The number of bridging members may vary,depending on the desired implementation, as may the orientations ofbridging members 72 a, 72 b, 72 c, 74 a and 74 b.

Stent 80 of FIG. 8 is formed by winding a first wire 81 around pins (notshown) on a mandrel. The geometry of the pins may be substantiallycircular to produce rounded apex sections, as in FIG. 1, or havestraight edges such as to produce apex sections having straight edges asin FIG. 8. In this manner, zig-zag members are formed and defined by asuccessive series of struts 84 connected by apex sections 85 alternatelypointing in opposite axial directions. The winding continues in thismanner around about half the circumference of stent 80. A second wire 86is introduced and wound around the remaining circumference of stent 80to complete a first hoop member 82 a. Where wires 81 and 86 overlie oneanother, they may be spot or linearly welded, thus to produce a pair ofhelical spines lending integrity to stent 80.

Any of the variations described herein may be combined with any othervariation described herein or known in the art, where practical, todevelop a stent architecture according to the present invention. Suchvariations may be uniformly utilized throughout the length of the stent,or as shown in FIG. 6F, the stent may comprise a plurality oflongitudinal sections, each of which may differ from another segmentwith respect to, for example without limitation: the size of one or moreof the apex section angles, the apex section axial length, the number ofapex sections per hoop, the number of connective spines, the spacing oroffset between facing apex sections, the type of connecting member, andthe uniformity of adjacent zigs. Moreover, the “struts” of each apexsection and the connections therebetween may be straight, as in a jaggedzig-zag configuration, or curved somewhat, such as when the overallstent section is more sinusoidal.

Although this invention has been described with reference to particularembodiments, it is not intended that this invention be limited thereto.Rather, the scope of the appended claims should be construed to coverall forms and variants of the invention as may be made by those skilledin the art without departing from the spirit and scope thereof.

What is claimed is:
 1. An intraluminal stent comprising: a plurality ofcircumferential hoops disposed in a helical succession along the axis ofsaid stent, each of said hoops defined by a single continuous filamentthat defines a helical arrangement of elements defined by a successiveseries of substantially straight struts connected by apex sectionsalternately pointing in opposite axial directions, and at least oneconnecting member between a first hoop and an adjacent hoop adapted toprevent relative axial movement between the first hoop and the adjacenthoop, the connecting member comprising at least a portion of a firststrut in one hoop connected to at least a portion of a second strut inan adjacent hoop, wherein the connecting member comprises one of: (a) adirect connection between a linear portion of the first strut that liesside by side with a linear portion of the second strut, or (b) aseparate bridging member having a first portion welded to the firststrut and a second portion welded to the second strut.
 2. The stent ofclaim 1, wherein at least one apex section comprises two struts attachedthereto and one strut is longer than the other strut.
 3. The stent ofclaim 1 further comprising a plurality of connecting members uniformlydistributed along the stent according to a predetermined helicalspacing.
 4. An intraluminal stent comprising: a plurality ofcircumferential hoops disposed in a helical succession along the axis ofsaid stent, each of said hoops comprising a helical arrangement ofelements defined by a successive series of substantially straight strutsconnected by apex sections alternately pointing in opposite axialdirections, and at least one connecting member between a first hoop andan adjacent hoop adapted to prevent relative axial movement between thefirst hoop and the adjacent hoop, the connecting member comprising atleast a portion of a first strut in one hoop connected to at least aportion of a second strut in an adjacent hoop, wherein the connectingmember comprises one of: (a) a direct connection between a linearportion of the first strut that lies side by side with a linear portionof the second strut, or (b) a separate bridging member having a firstportion welded to the first strut and a second portion welded to thesecond strut said stent further comprising a plurality of connectingmembers uniformly distributed along the stent according to a helicalspacing of once approximately every 450 degrees.
 5. An intraluminalstent comprising: a plurality of circumferential hoops disposed in ahelical succession along the axis of said stent, each of said hoopscomprising a helical arrangement of elements defined by a successiveseries of substantially straight struts connected by apex sectionsalternately pointing in opposite axial directions wherein each elementcomprises an axial length and the axial lengths of the plurality ofelements are generally uniform except for selected elements comprisingone or both ends of said stent, and at least one connecting memberbetween a first hoop and an adjacent hoop adapted to prevent relativeaxial movement between the first hoop and the adjacent hoop, theconnecting member comprising at least a portion of a first strut in onehoop connected to at least a portion of a second strut in an adjacenthoop, wherein the connecting member comprises one of: (a) a directconnection between a linear portion of the first strut that lies side byside with a linear portion of the second strut, or (b) a separatebridging member having a first portion welded to the first strut and asecond portion welded to the second strut.
 6. The stent of claim 5,wherein said end elements define a plane perpendicular to the axis ofsaid stent.
 7. An intraluminal stent comprising; plurality ofcircumferential hoops disposed in a helical succession along the axis ofsaid stent, each of said hoops comprising a helical arrangement ofelements defined by a successive series of substantially straight strutsconnected by apex sections alternately pointing in opposite axialdirections, and at least one connecting member between a first hoop andan adjacent hoop adapted to prevent relative axial movement between thefirst hoop and the adjacent hoop, the connecting member comprising atleast a portion of a first strut in one hoop connected to at least aportion of a second strut in an adjacent hoop, wherein the connectingmember comprises one of: (a) a direct connection between a linearportion of the first strut that lies side by side with a linear portionof the second strut, or (b) a separate bridging member having a firstportion welded to the first strut and a second portion welded to thesecond strut, said stent further comprising an end hoop disposed at eachend of said stent in which apex sections that point outwardly from saidstent lie in a common plane perpendicular to the axis of said stent. 8.The stent of claim 7, the end hoop comprising a plurality ofsubstantially straight struts connected by the apex sections, whereinthe struts of said end hoop have progressively shorter axial lengthleading to an end strut or adjacent apex sections have progressivelyshorter amplitudes leading to an end strut.
 9. The stent of claim 7,wherein the struts between apex sections of said end hoop progressivelyfurther overlap struts of an adjacent hoop leading to an end strut. 10.The stent of claim 9, wherein the end hoops each comprise an end strutthat is aligned adjacent to and connected to another strut of said endhoop.
 11. The stent of claim 10, wherein said end strut is connected tosaid another strut with a weld having a first weld length and saidconnecting members in said hoops that are not end hoops comprise a weldhaving a second weld length that is less than said first weld length.12. The stent of claim 11, wherein the end strut terminates short ofsaid common plane perpendicular to the axis of the stent on which liesaid end hoop apex sections that point outwardly from said stent.
 13. Anintraluminal stent comprising a plurality of circumferential hoopsdisposed in a helical succession along an axis of the stent, each hoopcomprising a helical arrangement of a successive series of substantiallystraight struts connected by apex sections alternately pointing inopposite axial directions, wherein at least one apex section comprisestwo struts attached thereto with one strut longer than the other strut,in which for each apex section comprising one strut longer than theother, the two struts lie on a cylindrical surface having a commonradius relative to a longitudinal axis of the stent, adjacentcircumferential hoops being engaged by at least one connector, a firstend of the at least one connector being parallel to and extending from asubstantially straight strut of a first circumferential hoop and asecond end of the at least one connector being parallel to and extendingfrom a substantially straight strut of a second circumferential hoop.14. The stent of claim 13, wherein said connecting members are parallelto and extend from said longer struts.
 15. The stent of claim 13,wherein an elongated strut of a first hoop lies adjacent to an elongatedhoop of an adjacent hoop for at least some axial distance to permitconnection therebetween.
 16. The stent of claim 13, wherein theconnecting member comprises a direct connection between a linear portionof the first strut that lies side by side with a linear portion of thesecond strut.
 17. The stent of claim 13, wherein the connecting membercomprises a separate bridging member having a first portion welded tothe first strut and a second portion welded to the second strut.
 18. Thestent of claim 13, wherein at least one apex section comprises anincluded angle, the apex sections arranged in a pattern in which theincluded angles are generally uniform except for selected apex sectionshaving non-uniform included angles to enable said portion of said firststrut to align with said portion of said second strut.
 19. Anintraluminal stent comprising: a helical arrangement of elements definedby a successive series of substantially straight struts connected byapex sections alternately pointing in opposite axial directions, whereinat least one apex section comprises two struts attached thereto with onestrut longer than the other strut, in which for each apex sectioncomprising one strut longer than the other, the two struts lie on acylindrical surface having a common radius relative to a longitudinalaxis of the stent; the elements forming a plurality of circumferentialhoops disposed in a helical succession along an axis of the stent, atleast one connecting member between a first hoop and an adjacent hoopadapted to prevent relative axial movement between the first hoop andthe adjacent hoop, the connecting member comprising at least a portionof a first strut in one hoop connected to at least a portion of a secondstrut in an adjacent hoop; and an end hoop disposed at each end of saidstent, each end hoop extending all the way around the circumference ofthe stent, each end hoop defined by a series of substantially straightstruts connected by apex sections alternately pointing in opposite axialdirections wherein apex sections that point outwardly from said stentlie in a common plane perpendicular to the axis of said stent.
 20. Thestent of claim 13 further comprising a plurality of connecting membersuniformly distributed along the stent according to a predeterminedhelical spacing.
 21. An intraluminal stent comprising: a helicalarrangement of elements defined by a successive series of substantiallystraight struts connected by apex sections alternately pointing inopposite axial directions, wherein at least one apex section comprisestwo struts attached thereto with one strut longer than the other strut,in which for each apex section comprising one strut longer than theother, the two struts lie on a cylindrical surface having a commonradius relative to a longitudinal axis of the stent; a plurality ofcircumferential hoops disposed in a helical succession along an axis ofthe stent; at least one connecting member between a first hoop and anadjacent hoop adapted to prevent relative axial movement between thefirst hoop and the adjacent hoop, the connecting member comprising atleast a portion of a first strut in one hoop connected to at least aportion of a second strut in an adjacent hoop; and a plurality ofconnecting members uniformly distributed along the stent according to ahelical spacing of once approximately every 450 degrees.
 22. The stentof claim 1, wherein the separate bridging member is parallel to a linearportion of the first strut and to a linear portion of the second strut.23. The stent of claim 1, wherein the separate bridging member isattached to a linear portion of the first strut and a linear portion ofthe second strut.
 24. The stent of claim 1, wherein the separatebridging member connects only two adjacent hoops.
 25. An intraluminalstent comprising: a plurality of circumferential hoops disposed in ahelical succession along the axis of said stent, all of said pluralityof circumferential hoops defined by a single continuous filament thatdefines a helical arrangement of elements defined by a successive seriesof substantially straight struts connected by apex sections alternatelypointing in opposite axial directions, and at least one connectingmember between a first hoop and an adjacent hoop adapted to preventrelative axial movement between the first hoop and the adjacent hoop,the connecting member comprising at least a portion of a first strut inone hoop connected to at least a portion of a second strut in anadjacent hoop, wherein the connecting member comprises one of: (a) adirect connection between a linear portion of the first strut that liesside by side with a linear portion of the second strut, or (b) aseparate bridging member having a first portion welded to the firststrut and a second portion welded to the second strut.
 26. A tubularstent having a tubular axis, said stent comprising: a plurality ofcircumferential hoops linearly disposed in succession along said axis,each of said hoops comprising elements defined by a successive series ofstruts connected by apex sections alternately pointing in opposite axialdirections to form a continuous series of similarly-oriented apexsections that point in a first direction, said similarly-oriented apexsections arranged in a helix in which each hoop comprises one 360-degreewrap of said helix, at least one pair of adjacent hoops being connectedto one another by a connecting member, said connecting member connectinga first strut, which is part of one of said connected adjacent hoops, toa second strut, which is part of the other of said adjacent hoops,wherein axially opposed apex sections of adjacent hoops are axiallyspaced from one another and said connecting member is a bridging memberwith a first end aligned with and connected to said first strut and asecond end aligned with and connected to said second strut.